My favorite 6922 tube for the VK-3i was the Tungsram. IMHO it took the preamp to another level. The only problem though was that I couldn't find a replacement set (for a reasonable price). I was never quite happy with my VK-3i after no longer running Tungsrams.
Go with a 6V6GT made by Visseaux. These are available from Upscale Audio.
Go with a 6V6GT made by Visseaux. These are available from Upscale Audio.